What is the RWIN setting?
The RWIN is the TCP Receive Window. TCP is a packet based transfer where data packets are moved in chunks rather than one at a time. The RWIN itself is a “buffer” that gathers the incoming data until it is full, then it moves the data to storage before refilling. Between fills, the computer sends acknowledgement packets “acks” that tell the sending computer that the data was correctly received. Increasing the RWIN means that more data is gathered on each transfer, followed by a blitz of acks, followed by more incoming data, and so on. Smaller RWIN sizes gather less data per fill, and thus send fewer acks, and then the cycle begins anew. The trick is in finding the proper RWIN for your line speed and latency. The TCP Receive Window has a default value of only about 8K bytes in Windows 95/98/NT, and about 16K bytes in Windows Me/2000/XP, which is adequate for relatively slow dialup modems and for high-speed networks with relatively low latency (e.g., less than 20 milliseconds). Increasin
